Spatial variability of soil development indices and their compatibility with soil taxonomic classes in a hilly landscape: a case study at Bandar village,Northern Iran

Soil complexity and its multivariable nature restrict the precision of soil maps that are essential tools for soil sustainable management. Most methods developed for reducing impurities of soil map units focus on soil external properties. Taking into account the soil internal properties like geochemical weathering indices could increase the map unit’s purity. However, the compatibility of these indices with Soil Taxonomic Classes has not been studied yet. This study has been performed in a hilly region with different soil types, vegetation and diverse topographic attributes to illustrate the spatial variability of soil weathering indices and their compatibility with Soil Taxonomic Classes. The grid sampling is at 100 m interval. Physico-chemical and total elemental analyses were performed on 184 and 56 soil samples respectively. Eight topographic attributes and 14 common soil development indices were determined. Principal components analysis (PCA) was done to identify the most important components. The results indicated that Morphological Index (MI) was the best index to show the degree of soil development in the studied region. Spatial distribution of Soil Taxonomic Classes showed relatively good compatibility with the first principal component (PC1), Vogt (V) and morphological indices. This study showed that using soil development indices with the conventional methods could be helpful tools in soil survey investigations     

Spatial distribution of land cover and vegetation activity along topographic gradient in an arid river valley, SW China

Anthropogenic activities have become more and more important in characterizing the landscape, but their impacts are still restricted by natural environments. This paper discusses the interactions of anthropogenic activity, vegetation activity and topography through describing the spatial distribution of land cover and vegetation activity （represented by Normalized Difference Vegetation Index, NDVI） along topographic gradient in a mountainous area of southwestern China. Our results indicate that the existing landscape pattern is controlled by anthropogenic activities as well as topographic factors. Intensive anthropogenic activities mainly occur in areas with relatively low elevation, gentle and concave slopes, as these areas are easy and convenient to attain for human. Because of the destruction by human, some land cover types （mainly grassland and shrub） are only found in relatively harsher environments. This study also finds that topographic wetness index （W） used in other places only reflects runoff generation capacity, but not indicate the real spatial pattern of soil water content in this area. The relationships between NDVI and W, and NDVI and length slope factor （LSF） show that runoff and erosion have complex effects on vegetation activity. Greater values of W and LSF will lead to stronger capacity to produce runoff and transport sediment, and thereby increase soil water content and soil deposition, whereas beyond a certain threshold runoff and erosion are so strong that they would destruct vegetation growth. This study provides information needed to successfully restore native vegetation, improve land management, and promote sustainable development in mountainous areas, especially for developing regions.     

Relationships between landslide types and topographic attributes in a loess catchment, China

Topographic attributes have been identified as the most important factor in controlling the initiation and distribution of shallow landslides triggered by rainfall.As a result,these landslides influence the evolution of local surface topography.In this research,an area of 2.6 km 2 loess catchment in the Huachi County was selected as the study area locating in the Chinese Loess Plateau.The landslides inventory and landslide types were mapped using global position system(GPS) and field mapping.The landslide inventory shows that these shallow landslides involve different movement types including slide,creep and fall.Meanwhile,main topographic attributes were generated based on a high resolution digital terrain model(5 m × 5 m),including aspect,slope shape,elevation,slope angle and contributing area.These maps were overlaid with the spatial distributions of total landslides and each type of landslides in a geographic information system(GIS),respectively,to assess their spatial frequency distributions and relative failure potentials related to these selected topographic attributes.The spatial analysis results revealed that there is a close relation between the topographic attributes of the postlandsliding local surface and the types of landslide movement.Meanwhile,the types of landslide movement have some obvious differences in local topographic attributes,which can influence the relative failure potential of different types of landslides.These results have practical significance to mitigate natural hazard and understandgeomorphologic process in thick loess area.     

基于TAVI的山区毛竹林LAI反演分析

本文采用地形调节植被指数（TAVI）,以RapidEye高分辨率多光谱遥感影像为数据源,对福建省永安市毛竹林山区进行了叶面积指数（LAI）地面实测、遥感建模及反演分析。通过TAVI与归一化植被指数（NDVI）、比值植被指数（RVI）的对比研究,结果表明：（1）毛竹林实测LAI与TAVI、NDVI和RVI线性回归的决定系数（R²）分别为0.6085、0.3156和0.4092,最佳非线性回归的R²分别提高到0.6624、0.5280和0.6497。LAI与NDVI或RVI非线性（U曲线）模型可以很好地解释LAI-VI的散点分布规律,但难以解决LAI-VI间因地形影响导致的“同物异谱”和“异物同谱”问题,因此,在山区大面积推广应用需慎重。（2）通过实测LAI的验证表明,LAI-TAVI回归模型可有效避免因地形影响导致的“同物异谱”和“异物同谱”问题。TAVI具有良好的削减地形影响作用,可用于山区植被LAI的遥感反演。     

地形复杂山区常用植被指数的地形校正对比

植被指数能反映地表植被生长、覆盖等情况,常作为反演植物生物物理参量的有效参数。然而,在地形复杂的山区,由于地形效应的影响,导致一些植被指数适用性受限。基于以上现状,本文以贵州省江口县为研究区,采用4种地形校正模型（Teillet-回归模型、Minnaert模型、C模型、SCS+C模型）对常用植被指数（SR、MSR、NDVI、SAVI、MSAVI、EVI）进行地形校正,以评价不同坡度条件下植被指数地形校正效果。结果表明：地形校正对缓解波段比形式的植被指数（SR、MSR、NDVI）地形效应的作用有限,而对非波段比形式的植被指数（SAVI、MSAVI、EVI）效果较好。另外,随着坡度增加,地形效应显著,地形校正效果也更明显：坡度较小时,波段比形式的植被指数无需进行地形校正,而建议非波段比形式的植被指数进行地形校正;坡度较大时,建议2类植被指数都进行地形校正,但非波段比形式的植被指数可能会发生过度校正现象。此外,地形校正后非波段比形式的植被指数与森林地上生物量线性回归模型的精度明显提高。因此,建议在地形复杂山区利用非波段比形式的植被指数进行定量反演时,先进行地形校正。     

Risk assessment of maize drought disaster in southwest China using the Environmental Policy Integrated Climate model

The East Asian monsoon has a tremendous impact on agricultural production in China. An assessment of the risk of drought disaster in maize-producing regions is therefore important in ensuring a reduction in such disasters and an increase in food security. A risk assessment model, EPIC(Environmental Policy Integrated Climate) model, for maize drought disasters based on the Erosion Productivity Impact Calculator crop model is proposed for areas with the topographic characteristics of the mountainous karst region in southwest China. This region has one of the highest levels of environmental degradation in China. The results showed that the hazard risk level for the maize zone of southwest China is generally high. Most hazard index values were between 0.4 and 0.5,accounting for 47.32% of total study area. However,the risk level for drought loss was low. Most of the loss rate was 0.1, accounting for 96.24% of the total study area. The three high-risk areas were mainlydistributed in the parallel ridge–valley areas in the east of Sichuan Province, the West Mountain area of Guizhou Province, and the south of Yunnan Province.These results provide a scientific basis and support for the reduction of agricultural drought disasters and an increase in food security in the southwest China maize zone.     

Spatial Prediction of Soil Salinity in a Semiarid Oasis: Environmental Sensitive Variable Selection and Model Comparison

Timely monitoring and early warning of soil salinity are crucial for saline soil management. Environmental variables are commonly used to build soil salinity prediction model. However, few researches have been done to summarize the environmental sensitive variables for soil electrical conductivity(EC) estimation systematically. Additionally, the performance of Multiple Linear Regression(MLR), Geographically Weighted Regression(GWR), and Random Forest regression(RFR) model, the representative of current main methods for soil EC prediction, has not been explored. Taking the north of Yinchuan plain irrigation oasis as the study area, the feasibility and potential of 64 environmental variables, extracted from the Landsat 8 remote sensed images in dry season and wet season, the digital elevation model, and other data, were assessed through the correlation analysis and the performance of MLR, GWR, and RFR model on soil salinity estimation was compared. The results showed that: 1) 10 of 15 imagery texture and spectral band reflectivity environmental variables extracted from Landsat 8 image in dry season were significantly correlated with soil EC, while only 3 of these indices extracted from Landsat 8 image in wet season have significant correlation with soil EC. Channel network base level, one of the terrain attributes, had the largest absolute correlation coefficient of 0.47 and all spatial location factors had significant correlation with soil EC. 2) Prediction accuracy of RFR model was slightly higher than that of the GWR model, while MLR model produced the largest error. 3) In general, the soil salinization level in the study area gradually increased from south to north. In conclusion, the remote sensed imagery scanned in dry season was more suitable for soil EC estimation, and topographic factors and spatial location also play a key role. This study can contribute to the research on model construction and variables selection for soil salinity estimation in arid and semiarid regions.     

Integrating multisource RS data and GIS techniques to assist the evaluation of resource-environment carrying capacity in karst mountainous area

The karst mountainous area is an ecologically fragile region with prominent humanland contradictions. The resource-environment carrying capacity(RECC) of this region needs to be further clarified. The development of remote sensing(RS) and geographic information system(GIS) provides data sources and processing platform for RECC monitoring. This study analyzed and established the evaluation index system of RECC by considering particularity in the karst mountainous area of Southwest China; processed multisource RS data(Sentinel-2, Aster-DEM and Landsat-8) to extract the spatial distributions of nine key indexes by GIS techniques(information classification, overlay analysis and raster calculation); proposed the methods of index integration and fuzzy comprehensive evaluation of the RECC by GIS; and took a typical area, Guangnan County in Yunnan Province of China, as an experimental area to explore the effectiveness of the indexes and methods. The results showed that:(1) The important indexes affecting the RECC of karst mountainous area are water resources, tourism resources, position resources, geographical environment and soil erosion environment.(2) Data on cultivated land, construction land, minerals, transportation, water conservancy, ecosystem services, topography, soil erosion and rocky desertification can be obtained from RS data. GIS techniques integrate the information into the RECC results. The data extraction and processing methods are feasible on evaluating RECC.(3) The RECC of Guangnan County was in the mid-carrying level in 2018. The midcarrying and low-carrying levels were the main types, accounting for more than 80.00% of the total study area. The areas with high carrying capacity were mainly distributed in the northern regions of the northwest-southeast line of the county, and other areas have a low carrying capacity comparatively. The coordination between regional resource-environment status and socioeconomic development is the key to improve RECC. This study explores the evaluation index system of RECC in karst mountainous area and the application of multisource RS data and GIS techniques in the comprehensive evaluation. The methods can be applied in related fields to provide suggestions for data/information extraction and integration, and sustainable development.     

基于不确定性迭代优化的山地植被遥感制图

山地因其较高的异质性和特殊的环境特征给遥感科学及其应用带来了诸多问题和挑战。为实现山地植被信息的精准提取,本研究选择部分滇西北山地区域作为研究区开展方法实验,利用高分辨率遥感影像数据和数字高程模型,结合分区分层感知思想,提出一种基于不确定性理论的山地植被型组分类制图方法。首先结合地形对研究区影像进行多尺度分割制作图斑;然后根据图斑特征使用随机森林方法进行分类,将分类结果与对应类别样本间的相似性作为优化目标,并构建混合熵模型定量计算图斑推测类型的不确定性,据此进行针对性的样本补充和分类模型的迭代优化。实验总体分类精度达90.8%,较迭代前提升了29.4%,Kappa系数达到0.875。在高不确定性区域,该方法相比使用一次性补样和随机补样方法的分类结果,精度分别提高了17%和13%。研究结果表明,通过人机交互的方式,基于不确定性理论为样本库融入增量信息的迭代优化方法能够有效提高植被型组分类的精度,相较于传统的样本选择方法具有更高的效率和更低的不确定性。     

CRWS-mountain Project: Coordinate remediation techniques and devices for water-soil pollution in mountain areas in China

Rural environmental governance is an important strategy to achieve the goal of building "green liveable villages" in China. However, studies on technology and devices for pollution remediation focus mainly on urban areas; in this regard, few studies have focused on rural areas, especially mountainous or hilly areas with interflow. Coordinate remediation techniques and devices for water-soil restoration in mountain areas(CRWS-mountain), a subproject of the "environmental monitoring and remediation in rural areas" project(ERM-rural project), was undertaken to develop techniques and devices for coordinating the restoration of water and soil in rural mountainous and hilly areas with interflow. The CRWS-mountain project will attempt to explore the mechanisms of pollutant transportation and transformation in the interflow-soil-surface water system, establish in-situ and heterotopic remediation systems in landfill, towns and surrounding areas, and construct a comprehensive system for "polluted soilinterflow-surface water" by integrating all the technologies and devices at Yanting, a typical rural mountainous hilly area in Sichuan, Southwest China. We expect that after using this comprehensive system, the water quality will meet the requirements for local water function zoning. The operation cost is 10% lower than that of the existing urban equipment.     

湖南省山丘区小流域山洪灾害危险性评价

本文采用信息量模型法研究湖南省山丘区小流域山洪灾害的危险性程度。信息量模型的最大意义是能从影响山洪灾害发生的众多因素中找到“最佳因素组合”。基于湖南省1955-2015年近60年的历史山洪灾害数据,结合地形、下垫面以及降雨条件,利用信息量模型按危险性程度高低划分出湖南省山丘区山洪灾害危险性的分布情况。研究结果表明,湖南省山丘区山洪灾害容易发生在坡度小于10°,高程小于100 m,起伏度小于30 m,土地覆被为人工表面,土壤类型为粘土以及降雨量在1584.3~1662.0 mm之间的区域。湖南省山丘区危险等级较高的地级市有永州市、郴州市、株洲市、岳阳市、娄底市以及长沙东部山区,经过混淆矩阵验证后,通过信息量方法建立的山洪灾害危险性评价模型准确率为75.36%,基本可信。     

Evaluation of the production-living-ecology space function suitability of Pingshan County in the Taihang mountainous area,China

A rational utilization of land is a matter of importance in sustainable development of mountainous area. The land function in mountainous areas has a close connection with space structure of ecology, production and living. To promote a harmonious development of the relationship between people and nature in mountainous areas, it is necessary to coordinate their relationships of space functions. Suitability evaluation of basic unit function associated with multi-scale space analysis is a prerequisite to a reasonable optimization of land function structure. In this study, an optimized evaluation index system of combination functions was introduced into the assessment of ecological spatial functional suitability in ecological fragile regions by adding three indicators, namely, soil erosion sensitivity, landscape ecological risk and ecological sensitivity. The principle of "taking high"(referred to a function with high suitability to be regarded as the main function of an evaluation unit) and ecological priority(referred to the case, supposing the suitability of a unit's three functions is consistent, the main function is determined to be the ecological function) were used to determine the main function of an evaluation unit. Pingshan County, China, located at the eastern foot of the Taihang Mountain, was targeted in this case study. The production-livingecology space(PLES) function in Pingshan was identified by applying our improved valuation indexes. Further, the functional suitability distribution of the combination of elements was obtained by using overlapping comprehensive analysis method, considering the tradeoff of the functional suitability of combination elements. The regions suitable for production/living were distributed in relatively flat piedmont plains, whereas the regions suitable for ecology were distributed in the mountain areas of middle and low altitudes. Therefore, to maintain a sustainable development in mountainous areas, an improved scheme of development for Pingshan should be to delineate ecologically fragile areas, to build ecological industrial parks near existing scenic spots, to protect basic agricultural production areas, and to increase investment in science and technology, including reasonable ecological compensation. This study can provide reference for the planning of sustainable development in the Taihang Mountain area and similar regions.     

低山丘陵区土地资源质量的影响因素分析——以朝阳地区为例

我国低山丘陵区具有丰富的土地资源和较大发展潜力,但也存在着经济发展水平落后、生态环境脆弱以及土地荒漠化、水土流失造成土地资源退化等不利因素, 直接威胁经济可持续发展。朝阳地区为较典型的低山丘陵区, 气候、地质背景、植被、水文以及社会历史背景、区域经济发展水平等自然和社会经济因素对该区土地资源质量具有不同程度的影响。正确认识并科学分析这类地区土地资源质量的各类影响因素, 对于合理利用并有效保护珍贵的土地资源、改善其日趋恶化的生态环境具有重要意义。     

耕地用途管制制度下的济南市耕地后备资源开发利用潜力研究

本文以济南市为研究对象,运用极限条件法初判济南市耕地后备资源宜耕性并划分潜力类型区,在此基础上,采用多因素综合评价方法测算宜耕后备资源的开发复耕难易程度并划分难易程度等级。结果表明：济南市各区县宜耕未利用地分布差异较大,从潜力类型区分布来看,丰富区和较丰富区主要分布在中南部山地丘陵区和南部沿黄区域,较匮乏区主要分布在北部平原区和南部山区,资源匮乏区主要为中部主城区附近。济南市易开发后备资源主要分布在中南部山地丘陵区。该研究可为济南市不同地域后备资源开发时序安排,科学编制耕地占补平衡和进出平衡方案提供参考。     

Impact of land expropriation on farmers' livelihoods in the mountainous and hilly regions of Sichuan,China

Research on the sustainable livelihoods of rural households is of great significance to mitigating rural poverty and reasonable land expropriation policy helps to realize better livelihoods and sustainable development. Scholars have conducted considerable research on the relationships between land expropriation and farmers. livelihoods. However,few quantitative studies have used the characteristics of villages as control variables to systematically analyze the impact of land expropriation on farmers.livelihood capital and strategy in the mountainous and hilly regions of China. This study uses the Partial Least Squares-Structural Equation Model(PLS-SEM)to systematically explain the impact of landexpropriation on farmers. livelihoods in mountainous and hilly regions of Sichuan in 2013, with the characteristics of the village including income,accessibility and terrain as control variables. The analysis uses both representative sample data of 240 rural households and spatial data calculated using a 30 m Digital Elevation Model(DEM) by Geographic Information System(GIS). Results are as follows:(1)The land expropriation characteristics are negatively affected by village accessibility. Villages with worse accessibility tend to have fewer land parcels and less land area expropriated. Additionally, land that is expropriated from inaccessible villages tends to receive less compensation.(2) Natural capital is negatively affected by number and area of land expropriation. Natural capital is not only directly affected by village accessibility, but also indirectlyaffected by village accessibility through the mediating effect of the number and area of land parcels expropriated.(3) Physical capital is positively affected by compensation for land expropriation, and negatively affected by village accessibility through compensation for land expropriation. The worse a village.s accessibility/location is, the less compensation it will receive for land expropriation,resulting in lower physical capital.(4) Financial capital is negatively affected by village accessibility indirectly through compensation for land expropriation. The better the village.s accessibility is,the greater is its compensation for land expropriation and, hence, the greater is its financial capital.(5)Social capital is directly and negatively affected by the number and area of land parcels expropriated, and is indirectly and positively affected by village accessibility through the number and area of land parcels expropriated. This study enhances our understanding of the characteristics of land expropriation and rural households. livelihood as well as the impact of land expropriation on rural households. livelihood. These findings provide reference for the formulation of proper policies related to land expropriation and the improvement of rural households. livelihoods in the mountainous and hilly regions of China.     

Quantification of restricting factors of agricultural development in Min County of Gansu,China

Agricultural development in povertystricken areas is a major problem affecting agricultural modernization in China. This study discusses the restrictive factors affecting agricultural development in impoverished areas in China. A typical impoverished mountainous area, Min County,was selected for a case study. A regression analysis on the factors and characteristics of agricultural development in Min County between 1982 and 2017 was performed in this study. Taking agricultural output as the dependent variable, we selected nine main inputs of agricultural production in impoverished mountainous areas as the independent variables. Ridge regression analysis was carried out by testing for unit root and co-integration to verify the equilibrium relationship of the data. The results showed that the real Gross domestic product(GDP)per capita, the non-grain area ratio, the proportion of government expenditure on agriculture support to total expenditure, and the amount of chemical fertilizer applied in unit cultivated land area were the four most significant factors. The proportion of government expenditure on agriculture support to total expenditure was a negative influence, whereas the other three significant factors had a positive influence on agricultural output. This study highlights about the most significant factors affecting the agricultural development of impoverished mountainous regions in China.     

机器学习方法在预测泉水潜在出露位置中的应用

泉水出露受到多种因素影响,在传统地质勘查手段之外,各种模型方法及影响因子预测手段,也被越来越多地应用于泉水的研究中.本文尝试利用机器学习的方法进行泉水出露位置的预测研究.根据北京市野外调查,确定了1378个测试样本点,选取了高程、坡度、坡向、地形湿度指数、径流强度指数、距河流距离、距断裂距离、岩性、归一化植被指数及土地...     

贵州省喀斯特地区泥石流灾害易发性评价

贵州省独特的喀斯特山地环境对地质灾害的孕育有其特有的作用机理。本文初选了10个相关因子进行GIS的方差分析及相关性分析,以筛选喀斯特山区泥石流灾害的主要影响因子及灾害易发性评价。结果表明,研究区内土壤侵蚀因子对泥石流灾害的贡献作用最为显著,断层的影响作用不明显。土壤侵蚀、坡度、坡向、岩石性质、土地利用方式、归一化植被指数（NDVI）、到沟谷的距离及>25 mm日数8个影响因子,具有良好的独立性和代表性,是研究区内泥石流易发性评价的最佳指标;泥石流主要分布在贵州西部云贵高原边境、北部大娄山、东北雾灵山及苗岭等地带,占全省面积的29.51%,贵州中部及东南部泥石流易发程度较低;极高易发区泥石流的分布密度是极低易发区的19倍,其主要的环境特征表现为坡度大、植被覆盖率较低,旱地与工矿用地分布多,土壤侵蚀严重;加强旱地、工矿用地及低植被覆盖区的合理利用及管理,是减少泥石流灾害发生的有效途径。     

Heterogeneity-diversity Relationships in Natural Areas of Yunnan,China

Understanding regional environmental heterogeneity(EH) and biodiversity relationships(heterogeneity-diversity relationships: HDRs) is the first step toward coupling environmental variables with biodiversity surrogates into regional systematic conservation planning. However, there is no universal method for determining regional HDRs that considers various environmental variables and biodiversity in different regions. This study selected 32 nature reserves as natural areas in Yunnan, China, to examine regional HDRs in Yunnan. We calculated 17 EH parameters(of soil, topography, and climate) and three(ecosystem, plant, and animal) biodiversity indices in the nature reserves. By examining the explanatory power of each EH parameter and area of the nature reserve, we identified the primary parameters and constructed an optimal model for each biodiversity index. The explanatory powers of these parameters varied for each biodiversity index, and those of climatic parameters were generally higher than soil and topographic heterogeneity ones. Heterogeneity of the temperature annual range, followed by area and heterogeneity of soil type, were important parameters for ecosystem diversity of Yunnan and the optimal model explained 56.9%. Plant diversity was explained 54.5% by its optimal model, consisting of heterogeneity of precipitation of the coldest quarter and annual precipitation. Heterogeneity of temperature annual range was important for animal diversity in Yunnan and explained 29.6% of its optimal model. This study suggests that EH parameters can be an effective surrogate for biodiversity, therefore, we suggested that the significance and role of climatically heterogeneous regions for the conservation of biodiversity in Yunnan should be further studied in the future.     

Soil organic carbon pools in particle-size fractions as affected by slope gradient and land use change in hilly regions, western Iran

This study was conducted to explore the effects of topography and land use changes on particulate organic carbon(POC),particulate total nitrogen(PTN),organic carbon(OC) and total nitrogen(TN) associated with different size primary particle fractions in hilly regions of western Iran.Three popular land uses in the selected site including natural forest(NF),disturbed forest(DF) and cultivated land(CL) and three slope gradients(0-10 %,S1,10-30 %,S2,and 30-50%,S3) were employed as the basis of soil sampling.A total of 99 soil samples were taken from the 0-10 cm surface layer in the whole studied hilly region studied.The results showed that the POC in the forest land use in all slope gradients was considerably more than the deforested and cultivated lands and the highest value was observed at NF-S1 treatment with 9.13%.The values of PTN were significantly higher in the forest land use and in the down slopes(0.5%) than in the deforested and cultivated counterparts and steep slopes(0.09%) except for the CL land use.The C:N ratios in POC fraction were around 17-18 in the forest land and around 23 in the cultivated land.In forest land,the silt-associated OC was highest among the primary particles.The enrichment factor of SOC,EC,was the highest for POC.For the primary particles,EC of both primary fractions of silt and clay showed following trend for selected land uses and slope gradients:CL> DF> NF and S3 > S2> S1.Slope gradient of landscape significantly affected the OC and TN contents associated with the silt and clay particles,whereas higher OC and TN contents were observed in lower positions and the lowest value was measured in the steep slopes.Overall,the results showed that native forest land improves soil organic carbon storage and can reduce the carbon emission and soil erosion especially in the mountainous regions with high rainfall in west of Iran.